What a star's light shows: spectra and color

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Table, Lab lines (NIST, air wavelengths), with columns Element, Lines (nm)

   Hydrogen, 656.3, 486.1, 434.0, 410.2; helium, 587.6; sodium, 589.0, 589.6; calcium, 393.4, 396.8.

2. 1.

   A star shows dark lines at 589.0, 589.6, 656.3 and 486.1 nm. Which elements does its outer gas contain, by Bo's reading?

   • Helium and calcium
   • Just hydrogen
   • Hydrogen and sodium
   • Just sodium
3. 2.

   A star shows dark lines at 587.6, 656.3 and 486.1 nm. Which elements match, by Esme's reading?

   • Just hydrogen
   • Helium and hydrogen
   • Calcium and helium
   • Sodium and hydrogen, since 587.6 is near 589
4. 3.

   A star shows dark lines at 393.4, 396.8, 589.0 and 589.6 nm. Which elements match, by Jun's reading?

   • Hydrogen and sodium
   • Helium and calcium
   • Calcium and sodium
   • Just calcium
5. 4.

   Peak = 2,898,000 nm·K ÷ temperature; Sun 5,772 K. The Sun's surface is about 5,772 K (IAU). Where does its light peak, by Kira's math?

   • About 5,772 nm
   • About 0.002 nm
   • About 1,000 nm
   • About 502 nm
6. 5.

   Peak = 2,898,000 nm·K ÷ temperature; star 3,000 K. A cool star's surface is about 3,000 K. Where does its light peak, by Luz's math?

   • About 290 nm, in the ultraviolet
   • About 966 nm, in the infrared
   • About 502 nm, like the Sun
   • About 3,000 nm
7. 6.

   A cloud of hot hydrogen glows in space with nothing bright behind it. What spectrum does Noah expect?

   • A smooth rainbow
   • Bright lines at hydrogen's wavelengths
   • Dark lines everywhere except hydrogen's
   • Dark lines at hydrogen's wavelengths
8. 7.

   A cool cloud of gas sits between Pia's telescope and a hot star. What appears in the spectrum?

   • Dark lines at the gas's own wavelengths
   • Bright lines at the gas's wavelengths
   • No lines, since the gas is too cool
   • Lines at random places
9. 8.

   Peak = 2,898,000 nm·K ÷ temperature; X peaks at 400 nm, Y at 700 nm. Star X peaks at 400 nm and star Y at 700 nm. About what are their surface temperatures, by Tala's math?

   • X about 7,200 K; Y about 4,100 K
   • X about 4,100 K; Y about 7,200 K
   • X about 1,160,000 K
   • Both about 5,800 K
10. 9.

    Star A is blue-white and peaks in the ultraviolet; star B is orange. Which is hotter, by Zee's reading?

    • Star A
    • Star B, which peaks at a longer wavelength
    • They are equally hot
    • Star B, since orange looks warm
11. 10.

    A blue star and a red star both show hydrogen's dark lines. What can Ari say?

    • Color shows which elements a star has
    • Both contain hydrogen; their colors differ with temperature
    • The red star lacks hydrogen
    • The blue star is the cooler one